1. Field of the Invention
This invention relates to novel 1,1,1-trioxyalkanes capable of stabilizing synthetic resin compositions against the deleterious effects of actinic light, to stabilizer compositions comprising these 1,1,1-trioxyalkanes, and to stabilized synthetic resin compositions in which a stabilizing quantity of such 1,1,1-trioxyalkanes are incorporated. More particularly, the invention relates to novel 1,1,1-trioxyalkanes of sterically hindered piperidino alcohols, that is 1,1,1-trioxyalkanes of alcohols in which the alcohol group is linked to the 4-position of the piperidine ring in a 2,2,6,6-tetraalkylpiperidine compound.
2. Prior Art
A multitude of sterically hindered piperidine compound stabilizers has been disclosed, following upon the pioneer disclosure by K. Murayama et al in U.S. Pat. No. 3,640,928 of Feb. 8, 1972. Murayama et al disclosed the stabilization of synthetic polymers against photo- and thermo-deterioration by incorporating therein, in a sufficient amount to prevent such deterioration, a piperidine derivative having the general formula ##STR1## or a salt thereof.
In the above formula I:
R.sub.1 and R.sub.2, which may be the same or different, each are an alkyl group such as methyl, ethyl, isopropyl or dodecyl, or they form, together with the carbon atom to which they are attached, a saturated alicyclic group such as ##STR2## or a group of the formula ##STR3## n is an integer of 1 to 3 inclusive; and when n is 1, R.sub.3 is an acyl group derived from an aliphatic, alicyclic or heterocyclic monocarboxylic acid; an N-substituted carbamoyl group derived from an n-substituted carbamic acid; an N-substituted thiocarbamoyl group derived from an N-substituted thiocarbamic acid; a monovalent group obtained by removing a hydroxyl group from an oxoacid; an alkyl group; a cycloalkyl group; an aralkyl group; an aryl group; or a group of the general formula ##STR4## (wherein R.sub.1 and R.sub.2 are as defined above); when n is 2, R.sub.3 is a diacyl group derived from an aliphatic, alicyclic, aromatic or heterocyclic dicarboxylic acid; a dicarbamoyl group derived from dicarbamic acid; a bisthiocarbamoyl group derived from bisthiocarbamic acid; a carbonyl group; a divalent group obtained by removing two hydroxyl groups from an oxacid; an alkylene group; an arylene group; or an arylenedialkylene group; and PA0 when n is 3, R.sub.3 is a triacyl group derived from an aliphatic, alicyclic, aromatic or heterocyclic tricarboxylic acid; a tricarbamoyl group derived from tricarbamic acid; a tristhiocarbamoyl group drived from tristhiocarbamic acid; a trivalent group obtained by removing three hydroxyl groups derived from an oxacid; an alkanetriyl group; arenetriyl group; or an arenetriyltrialkylene group. PA0 n is an integer of 1 through 4 inclusive; and PA0 R.sub.3 represents, PA0 and also disclosed a process which comprises reacting a 4-piperidinol derivative having the formula ##STR7## wherein R.sub.1 and R.sub.2, and X have the same meanings as above with a lower alkyl ester of an acid having the formula EQU R.sub.3 --(OR.sub.4).sub.n PA0 wherein R.sub.3 and n have the same meanings as above and R.sub.4 is a lower alkyl group, e.g., methyl, ethyl or propyl in the presence of an alcoholysis catalyst.
In U.S. Pat. No. 3,840,494 of Oct. 8, 1974, Murayama et al disclosed as stabilizers acid esters of 4-piperidinol derivatives having the formula ##STR5## wherein R.sub.1 and R.sub.2 may be the same or different and represent an alkyl group of 1 to 4 carbon atoms or they may form, together with the carbon atom to which they are attached, a saturated alicyclic group or the group of the formula ##STR6## X is hydrogen atom, oxygen free radical (--O) or an alkyl group of 1 to 4 carbon atoms;
when n is 1, an acyl group derived from an aliphatic or aromatic monocarboxylic acid, PA1 when n is 2, a diacyl group derived from an aliphatic or aromatic dicarboxylic acid or carbonyl group, PA1 when n is 3, a triacyl group derived from an aliphatic or aromatic tricarboxylic acid or a trivalent group obtained by eliminating three hydroxyl groups from phosphoric acid, phosphorous acid or boric acid, and PA1 when n is 4, a tetraacyl group derived from an aromatic tetracarboxylic acid or a tetravalent group obtained by eliminating four hydroxyl groups from orthosilicic acid, PA1 2,2,6,6-Tetraalkyl piperidine compounds do not impart color to the polymer, and act as quenchers. However, the available piperidine compounds are unsatisfactory in stabilizing effectiveness, are so volatile that they are lost when the polymer is heated at elevated temperatures, and are extracted by water. PA1 2,2,6,6-Tetraalkyl piperidine compounds of high molecular weight are said to have improved properties in these respects. Several types of polymers have been dscribed. Polyesters containing hindered piperidyl groups in the molecule are proposed in Japanese patent publication Kokai No. 141,883/77. Acrylate polymers containing hindered piperidyl groups are proposed in Japanese patent publication Kokai No. 157,612/80. While the volatility of these compounds is low, their stabilizing effectiveness is unsatisfactory.
In U.S. Pat. No. 3,899,464 of Aug. 12, 1975, Murayama et al disclosed piperidine spiro comounds having the formula ##STR8## wherein R.sub.1 represents hydrogen atom, an alkyl group, a substituted alkyl group, an alkenyl group, an alkenyl group, a substituted or unsubstituted aralkyl group, an aliphatic acyl group, an alkoxycarbonyl group or an aralkoxycarbonyl group, n is an integer of 1 to 4; when n is 1, R.sub.2 represents hydrogen atom, an aliphatic, aromatic or heterocyclic monoacyl group, an alkyl group, an alkenyl group, an alkynyl group, an aralkyl group, an aryl group, an alkoxyalkyl group, an epoxyalkyl group, an alkoxysulfonylalkyl group, N-substituted carbamoyl group, a N-substituted thiocarbamoyl group, a monovalent group from an oxoacid or group ##STR9## in which R.sub.3 represents hydrogen atom, a lower alkyl group or phenyl group and R.sub.4 represents an alkyl group; when n is 2, R.sub.2 represents carbonyl group, an aliphatic or aromatic diacyl group, an alkylene group, an alkenylene group, an alkynylene group, an aralkylene group, a N-substituted dicarbamoyl group or a divalent group from an oxoacid; when n is 3, R.sub.2 represents an aromatic triacyl group or a trivalent group from an oxoacid; and when n is 4, R.sub.2 represents an aromatic tetraacyl group, and A represents a group ##STR10## in which R.sub.5 represents hydrogen atom or a lower alkyl group or, when n is 1, R.sub.5 may represent toegether with R.sub.2 a group ##STR11## in which R.sub.6 represents the same group as defined in R.sub.1 and may be the same or different from R.sub.1 or a group ##STR12## in which m is 1 or 2 and R.sub.7 represents hydrogen atom or, when n and m are 1, R.sub.7 represents methylene group together with R.sub.2.
Esters of 2,2,6,6-tetraalkylpiperidine-4-alcohols in which the piperidine ring carries an additional hydrocarbon substituent on a ring carbon atom have been disclosed by N. Soma et al in U.S. Pat. No. 4,075.165 of Feb. 21, 1978.
Additional stabilizers characterized by 2,2,6,6-tetraalkylpiperidine structure connected through a 4-oxygen atom are disclosed in U.S. Pat. Nos. 4,021,432, 4,087,406, 4,096,114, 4,101,508, 4,102,858, 4,105,626, 4,110,305, 4,116,927, 4,128,608, 4,136,081, 4,136,083, 4,141,884, 4,148,783, 4,148,784, 4,154,722, 4,166,803, 4,177,186, 4,194,989, 4,197,236, 4,198,534, 4,210,578, 4,212,974, 4,221,704, 4,223,148, 4,231,921, 4,233,412, 4,234,699, 4,234,700, 4,250,268, 4,263,202, 4,265,805, 4,293,467, 4,293,468, 4,294,949, 4,308,362, 4,345,493, 4,360,675, 4,369,321, 4,377,690, and 4,378,443 as well as British Pat. No. 1,588,259 and British published patent application No. 2,014,586 among others.
There have also been disclosures of 2,2,6,6-tetraalkylpiperidine derivative stabilizers in which a subsituent is connected to the 4-position of the piperidine ring through carbon (see U.S. Pat. Nos. 3,474,608 and 4,130,710) or through nitrogen (see U.S. Pat. Nos. 3,684,765, 3,925,376, and 4,104,248).
Polymeric stabilizers in which a 2,2,6,6-tetraalkylpiperidine structure is connected through a 4-oxygen on the piperidine ring have been disclosed. The tetraalkylpiperidine structure can be part of the polymeric chain or can occur as a side-chain substituent in a regular or randomly repeating manner. Representative disclosures include J. Rody et al U.S. Pat. Nos. 4,233,412, 4,234,700 and 4,250,268; N. Kubota et al, U.S. Pat. No. 4,413,076; and F. Fu et al U.S. Pat. No. 4,413,096. In much of the voluminous art summarized above, there appear statements to the effect that previously known 2,2,6,6-tetraalkylpiperdine compound stabilizers are unsatisfactory, as illustrated by the following, quoted from Kubota et al:
Nevertheless, the market for stabilizers that do not impart color remains dominated by the earliest introduced products, in particular the compound bis(2,2,6,6-tetramethylpiperidin-4-yl)sebacate of Murayama et al U.S. Pat. No. 3,640,928. In spite of its bulk, therefore, the art is not helpful to the polymer user in search of better stabilization against the deteriorative effects of exposure to active light. Orthoformate esters as a class have been known for over a century. For a review of methods of preparation and interconversion of orthoformates, the article by R. H. DeWolfe, Synthesis 1974, pages 153-160 can be consulted. In particular, the author notes that transesterification of trimethyl and triethyl orthoformate occurs smoothly with most primary alcohols while transesterifications involving secondary alcohols are slow, and can remain incomplete.
G. Kesslin et al in U.S. Pat. No. 3,415,846 of Dec. 10, 1968 disclosed the reaction of a trialkyl orthoformate with a 1,1,1-tris(hydroxymethyl)alkane to give a bicyclic orthoformate such as 4-methyl-2,6,7-trioxabicyclo(2.2.2)octane.
L. L. Wood in U.S. Pat. No. 3,514,428 of May 26, 1970 disclosed orthoformate ester heat stabilizers for polyvinyl chloride resin, prepared by reaction of triethyl orthoformate with a higher alcohol such as benzyl alcohol. Similarly, G. Kesslin et al in U.S. Pat. No. 3,546,188 of Dec. 8, 1970 disclosed orthoformate esters such as triallyl orthoformate to be effective in polyvinyl chloride stabilization against deterioration under thermal stress. The orthoformate ester stabilizers disclosed by Wood and by Kesslin contained only carbon, hydrogen, and oxygen. I. Bechara et al in U.S. Pat. No. 3,879,456 of Apr. 22, 1975 disclosed aminoalkanol orthoformate ester activators for preparation of polyurethanes and cured epoxy resins, for example tris(2(dimethylamino)ethyl)orthoformate and bis(2-(dimethylamino)ethyl methyl orthoformate by reaction of trimethyl orthoformate with 2(dimethylamino)ethanol.
R. A. Swaringen, Jr. et al in Journal of Organic Chemistry, 1980, pages 3986-89, disclosed the reaction of orthoformate esters with cyclic amines at the ring nitrogen to give N-orthoamide such as tripiperidinomethane from piperidine and trimorpholinomethane from morpholine. N. Soma et al in U.S. Pat. Nos. 4,075,165 of Feb. 21, 1978 and 4,141,883 of Feb. 27, 1979 disclosed a different reaction of certain piperidine compounds with triethyl orthoformate. Soma et al disclosed that the piperidine compounds of formula (I), (II) or (III) wherein X represents a formyl group can be prepared by reacting a corresponding compound wherein X represents a hydrogen atom with ethyl orthoformate in the presence of an acid catalyst.
Soma's formulas (I), (II), and (III) refer to, respectively, Soma's 3- and/or 5-substituted-2,2,6,6,-tetrasubstituted-4-piperidinol derivative stabilizer and the substituted piperidin-4-one and piperidin-4-ol precursors thereof, as shown: ##STR13## wherein:
R.sup.a and R.sup.b are the same or different and each represents a hydrogen atom, a lower alkyl group, an alkenyl group, an alkynyl group or an aralkyl group, provided that R.sup.a and R.sup.b do not simultaneously represent hydrogen atoms;
R.sup.c and R.sup.d are the same or differnet and each represents a lower alkyl group;
R.sup.3 represents an alkyl group;
R.sup.f represents an alkyl group, a phenyl group, an aralkyl group or a 5- or 6-membered aromatic heterocyclic group containing an oxygen, sulphur or nitrogen atom; or
R.sup.e and R.sup.f, together with the carbon atom to which they are attached, represent a cycloalkyl group or a group of the formula: ##STR14## (wherein R.sup.g and R.sup.h are the same or different and each represents a hydrogen atom or a lower alkyl group, provided that R.sup.h does not represent a hydrogen atom when R.sup.g represents a lower alkyl group; R.sup.i and R.sup.j are the same or different and each represents a lower alkyl group; and X is as hereafter defined);
X represents a hydrogen atom, an oxyl radical, an alkyl group, an alkenyl group, an alkoxyalkyl group, an aralkyl group, which is unsubstituted or which has one or more substituents in its aryl moiety, a 2,3-epoxypropyl group, a group of formula --CH.sub.2 COOR.sup.1 (wherein R.sup.1 represents an alkyl group, an alkenyl group, a phenyl group, an aralkyl group or a cyclohexyl group), a group of formula: ##STR15## (wherein R.sup.2 represents a hydrogen atom, a methyl group or a phenyl group and R.sup.3 represents a hydrogen atom or an acyl group O, an aliphatic acyl group or a group of formula --COOR.sup.4 (wherein R.sup.4 represents an alkyl group, a benzyl group or a phenyl group); Y represents an organic or inorganic group or atom having a valency of from 1 to 4 and having essentially no adverse effect on the polymer stabilization activity; and n is an integer of from 1 to 4 inclusive, ##STR16## (wherein R.sup.a, R.sup.b, R.sup.c, R.sup.d, R.sup.e, R.sup.f and X are as defined above, provided that X does not represent an oxyl radical), ##STR17## (wherein R.sup.a, R.sup.b, R.sup.c, R.sup.d, R.sup.e, R.sup.f and X are as defined above).